Halotrifluorocyclopropenes

ABSTRACT

HALOTRIFLUOROCYCLOPROPENES HAVING THE FORMULA   1,2,3-TRI(F-),3-X-1-CYCLOPROPENE   WHEREIN X IS FLUORINE, CHLORINE OR BROMINE CAN BE PREPARED BY DEHALOGENATION OF   1,2,3-TRI(F-),1,2-DI(X-),3-Y-CYCLOPROPANE   WHEREIN Y IS CHLORINE OR BROMINE, OR BY DEHYDROHALOGENATION OF   1,2,3-TRI(F-),1-Y,2-X-CYCLOPROPANE   THE COMPOUNDS CAN BE COPOLYMERIZED WITH ETHYLENICALLY UNSATURATED MONOMERS TO FORM USEFUL POLYMERS, AND ARE ALSO USEFUL AS INSECTICIDES.

Patented Jan. 11, 1972 3,634,525 HALOTRIFLUOROCYCLOPROPENES Archie E. Barkdoll, Hockessin, Del., and Peter B. Sargent, Waynesboro, Va., assignors to E. I. du Pont de Nemours and Company, Wilmington, Del.

No Drawing. Original application May 6, 1966, Ser. No. 548,068, now Patent No. 3,418,275, dated Nov. 26, 1968. Divided and this application May 28, 1968, Ser.

Int. Cl. C07c 23/04 U.S. Cl. 260-648 F 3 Claims ABSTRACT OF THE DISCLOSURE Halotrifluorocyclopropenes having the formula wherein X is fluorine, chlorine or bromine can be prepared by dehalogenation of F\ /X F-C-CF The compounds can be copolymerized with ethylenically unsaturated monomers to form useful polymers, and are also useful as insecticides.

RELATED APPLICATIONS This application is a division of application S.N. 548,- 068 filed May 6, 1966.

DESCRIPTION OF THE INVENTION This invention relates to fiuorinated cyclopropenes, their copolymers and the preparation of both.

More specifically, the invention is directed to 3-halotrifluorocyclopropenes and their copolymers with polymerizable ethylenically unsaturated monomers. The novel monomers of this invention are represented by the structural formula wherein X is fluorine, chlorine or bromine. Preferably X is fluorine.

The monomers of the invention canbe prepared by two methods, one being the dehydrohalogenation of a cyclopropane of the formula and the other, which is the preferred method, being the dehalogenation of a compound of the formula In these formulas X is as defined previously and Y is chloroine or bromine. The dehydrohalogenation and dehalogenation processes are, in general, well-known reactions and are discussed in such references as Chemie and Technologic Aiphatischer Fluroorganischer Verbindungen, D. Osteroth, F. Enke, Verlag, Stuttgart, 1964, pp. 26-37. Dehydrohalogenation reactions are discussed in Aliphatic Fluorine Compounds, A. M. Lovelace et al., Reinhold Publishing Corp., New York, N.Y., 1958, pp. 101-104; and in Tetrahedron Letters, No. 29, 1945 (1964), M. Schlosser et a1. Dehalogenation reactions are discussed in Aliphatic Fluorine Compounds, supra, pp. 104-105.

In the dehydrohalogenation reaction, the eyclopropane compound is reacted with a base. Normally an excess of base is used, although the reaction proportions are not critical. Neither pressure nor reaction time is critical, and usually atmospheric pressure and a time suflicient to form the product are employed. Effective bases include molten alkali or alkaline earth metal hydroxides; alkali or alkaline earth metal hydroxide suspensions in, e.g., ethers such as dibutyl ether, dioctyl ether, dioxane, diethyl ether and the like; lower alkyl alkali metal (e.g., methyllithium, butyllithium, propylsodium, or ethylpotassium) suspensions in others such as in the preceding sentence, or in hydrocarbons such as benzene, hexane, cyclohexane, and the like; or sodium hydride in dimethylformamide. Reaction temperatures depend upon the base employed and will range between 10 to about 165 C., and preferably between 25 and 165 C. Representative hydroxides include the hydroxides of lithium, potassium, sodium, cesium, calcium, magnesium, barium, strontium, and the like.

In the preferred dehalogenation method, the cyclopropane compound is reacted with, preferably, an excess of a dehalogenation reagent such as zinc dust, activated with zinc bromide, mercuric chloride or hydrochloric acid, in ethanol; zinc in tetrahydrofuran or acetic anhydride; magnesium in tetrahydrofuran; and the like. As can be seen, the reaction media include alcohols, ethers, and the like. Pressure is not critical and atmospheric pressures are usually employed. The reaction proceeds in air or under an inert atmosphere such as nitrogen or helium at temperatures of between about 25 to 60 C. Reaction times of several hours up to several days are ordinarily used.

The novel monomers so produced are colorless gases or low-boiling liquids, e.g., tetrafluorocyclopropene boils at about 13 C., melts at about 60 C. and is stable for several hours at C., and is stable indefinitely at room temperature. Thus, in both processes the novel products can be obtained by trapping the gases produced in the reaction and separating the novel monomer from reactants and byproducts by conventional means such as fractional distillation or gas chromatography. In general, they are explosive and easily ignited. Thus, special precautions should be taken throughout the preparation.

The novel polymers of this invention are copolymers of the above-described novel monomers with polymerizable ethylenically unsaturated monomers and are prepared by conventional free-radical initiated polymerization.

The ethylenically unsaturated monomers include unsaturated hydrocarbons such as ethylene, propylene, isobutylene, and styrene; halogenated compounds such as 1,1-difluoroethylene (vinylidene fluoride), 1,1-difluoro-2- chloroethylene, trifiuoroethylene, chlorotrifiuoroethylene,

hexafluoropropene, and particularly the vinyl halides such as vinyl fluoride, vinyl chloride, and vinyl bromide; vinyl carboxylates, such as vinyl formate, acetate, vinyl benzoate, and vinyl esters of higher aliphatic carboxylic acids; esters, nitriles, amides, anhydrides, and acid halides of a-methylene monocarboxylic acids such as methyl methacrylate, methyl acrylate, methyl-a-chloroacrylate, acrylonitrile, methacrylic amides, methacrylic acid anhydride, and methacrylic acid fluoride; vinyl ethers such as vinyl ethyl ether and vinyl butyl ether; vinyl ketones, such as vinyl methyl ketone and vinyl phenyl ketone; N-vinyl compounds, such as N-vinyl succinimide, N-vinylphthalimide and N-vinyl carbazole; the esters of vinylene dicarboxylic acids, such as dimethyl fumarate and diethyl fumarate; compounds having more than one ethylenic double bond, such as 2-flu0ro-1,3-butadiene, 2-chloro-1,3- butadiene, and 2-cyano-l,3-butadiene, and compounds containing acetylenic unsaturation in addition to the ethylenic double bond, for example, monovinylacetylene, divinylacetylene, and vinyl (ethinyl)-carbinols.

'Of the classes of polymerizable ethylenically unsaturated monomers above, terminally unsaturated monomers such as vinyl monomers are preferred. Thus, these preferred classes include the vinyl halides, vinyl carboxylates, esters, nitriles, amides, anhydrides and acid halides of tat-methylene monocarboxylic acids, and vinyl ethers. Especially preferred are fluoroolefin comonomers, such as tetrafluoroethylene, chlorotrifluoroethylene, vinylidene fluoride, vinyl fluoride, trifluoromethyl trifluorovinyl ether, hexafluoropropylene, and the like.

The copolymers are prepared by reacting one or more of the monomers of this invention With one or more of the ethylenically unsaturated monomers, either in bulk or in an inert media such as acrylonitrile, 1,1,2-thichloro-1, 2,2-trifluoroethane, water, and the like, in the presence of a free-radical initiator such as azoisobutyronitrile, benzoyl peroxide, di-t-butyl peroxide, dinitrogen difluoride, perfluoropropionyl peroxide, and the like. The reaction conditions are well known and are employed as described in, for example, U.S. Pat. 2,468,664. Reactant ratios are not critical and thus, monomer ratios in the resulting copolymers are likewise not critical.

The following examples further illustrate the novel monomers and copolymers of this invention and their preparation.

EXAMPLE 1 Tetrafluorocyclopropene and 3-chlorotrifiuorocyclopropene Potassium hydroxide (20 g.) was heated by an oil bath to 160-165 C. in a 50-ml. 3-neck round-bottom flask equipped with an addition funnel, magnetic stirrer, and water condenser leading to a Dry Ice-acetone cooled trap. l-chloro-1,2,3.,3-tetrafluorocyclopropane (1.0 g., 0.067 mole) was added rapidly to the stirring molten potassium hydroxide. The reaction mixture turned dark and gas evolution occurred. Vapor phase chromatography of the gaseous product showed the presence of several products, two of which were identified as being tetrafluorocyclopropene and 3chlorotrifluorocyclopropene.

EXAMPLE 2 Tetrafluorocyclopropene and S-flutrifluorocyclopropene Aqueous potassium hydroxide (150 g. in 30 ml. of H was heated to 90 C. in a 500-ml. 3-neck round-bottom flask equipped with a mechanical stirrer, a 50-ml. addition funnel, and a cold water condenser leading to a 50-ml. trap cooled in Dry Ice-acetone. 1-chloro-1,2,3,3- tetrafluorocyclopropane (49.5 g., 0.33 mole) was slowly added to the stirring mixture over 30 minutes. There was obtained 21 ml. of product (34 g.) which contained 14% perfluorocyclopropene, 86% l-chloro-l,2,3,3-tetraflu0rocyclopropane and a small amount of 3-chloro-l,2,3-trifluorocyclopropene, as determined by vapor phase chromatography. Distillation of the product through a 40-cm. low temperature distillation column gave perfluorocyclopropene (4.0 g., B.P. 22 to 15 C.).

EXAMPLE 3 Tetrafluorocyclopropene and 3-chlorotrifluorocyclopropene F FCl Potassium hydroxide 30 g.) was heated to 165 C. in a 50-ml. 3-neck round-bottom flask equipped with an addition funnel, a mechanical stirrer, and a reflux condenser with a line heading to a trapcooled in Dry Ice-acetone followed by a trap cooled in liquid Na. The system was continuously swept with a slow flow of helium. l-chloro-l,2,3,3tetrafluorocyclopropane (2 g., 0.012 mole) was quickly added to the stirring molten potassium hydroxide. There was obtained 0.7 ml. of liquid in the Dry Ice cooled trap which Was shown to be a mixture of perfluorocyclopropene, 3-chl0rotrifluorocyclopropene and starting material by vapor phase chromatography and infrared spectrometry. Perfluorocyclopropene and 3-chlorotrifluorocyclopropene were separated by vapor phase chromatography and subject to mass spectrometry for confirmation of structures.

EXAMPLE 4 Perfluorocyclopropene F2 F2 F/ F KOH Aqueous potassium hydroxide (200 g. in 400 ml. of H 0) was heated to C. in a 1-liter 3-neck roundbottom flask equipped with a mechanical stirrer, gas inlet tube reaching below the surface of the liquid, and a condenser leading to a 50-ml. trap cooled in Dry Iceacetone. Pentafluorocyclopropane (38 g., 0.29 mole) was slowly bubbled through the stirring solution (6 hours). The final portion was passed through by sweeping with N for 15 minutes. There was obtained 15.5 ml. of product (25 g.) which was found to consist of 24% perfiuorocyclopropene and 86% pentafluorocyclopropane by vapor phase chromatography.

EXAMPLE 5 Perfluorocyclopropene 1.7 ml. of liquid in the trap which was shown to be a mixture of perfluorocyclopropene (67%) and starting material (33%) by vapor phase chromatography.

EXAMPLE 6 Tetrafluorocyclopropene Zinc dust (220 g., 3.3 mole) and zinc bromide (22 g.) were suspended in ethanol (300 ml.) in a 1-liter 3-neck round-bottom flask equipped with a 250-ml. addition funnel, mechanical stirrer, and cold water condenser leading to a 50-ml. trap cooled in Dry Ice-acet-one, and heated to 55 C. under N 1,2-dichloro-1,2,3,3-tetrafluorocyclopropane (136 g., 0.74 mole) in ethanol (75 ml.) was slowly added to the stirring suspension. After 18 hours the system was swept with N for minutes. The product (50 ml.), collected in the trap, was distilled through a 40-cm. low temperature distillation column to give unreacted 1,2-dichloro-1,2,3,3-tetrafluorocyclopropane (27.1 g., 0.15 mole, 80% conversion) and tetrafluorocyclopropane (B.P. 10 to +3 C., 56 g., 0.50 mole, 85% yield).

TABLE I.COPOLYMERS OF PERFLUOROCYCLOPROPENE Reaction Weight Monomer Example time copolymer Percent perfluoroo. Vmyl monomer Mmoles (hrs.) b (mg) F cyclopropene 0 a 3. 6 21 151 87.18 3. 31 a 2.1 8 48 38. 30 3.09 3. 6 a 78 33. 68 2.02 B 2. 9 20. 5 23 2. 1 8 4 8 e 1. 4 8 48 6. 24 17. 7 f 1.3 8 126 2. 87 24. 2 l1 2. 3 (s) 114 1.20 117 2. 3 8 110 1. 23 115 2. 1 8 200 39. 95 1. h 1. 5 8 191 38. 30 3. 09 3. 4 8 25. 86 3. 24 3. 4 8 33. 78 2. 02

a Equimolar amounts of perfluorocyclopropene. b Heated at 8085 C. o Mole ratio calculated from elemental F analysis. d No elemental F analysis. 6 Not weighted. f 1.3 mmoles styrene, 2.1 mmoles perfluorocyclopropene. g Allowed to stand at; room temperature for 4 days. 1.5 mmoles vinyl acetate, 2.1 mmoles perfluorocyclopropene.

EXAMPLE 7 EXAMPLE 23 Perfluorocyclopropene/methyl vinyl ether copolymer Perfluorocyclopropene (16 moles), methyl vinyl ether (16.7 mmoles), and benzoyl peroxide (0.01 g., 4.5 l0* moles) were sealed in a glass tube (200 mm. x 8 mm. ID. x 10 mm. OD.) and heated at 85 C. for 8 hours to provide a white solid copolymer, 1.94 g., 83% yield) containing 41.6% fluorine. This corresponds to a ratio of 1.2:1 methyl vinyl ether:perfluorocyclopropene. The copolymer was soluble in diethyl ether, acetone, benzene, and tetrahydrofuran. Clear, self-supporting films were pressed at 200 C. and also cast from benzene solution. The copolymer had an inherent viscosity of 0.32 (0.1% benzene solution at 25 0.).

EXAMPLE 8 Perfluorocyclopropene/ methyl vinyl ether copolymer Methyl vinyl ether (3.0 mmoles), perfluorocyclopropene (3.0 mmoles) and azoisobutyronitrile (0.0036 g., 2.2 10 moles) were sealed in a glass tube (18 mm. x 4 mm. ID.) and heated at 65 C. for 8 hours. There was obtained 0.59 g. of white solid copolymer containing 42.23% R; this corresponds to a molar ratio of 1.17:1 methyl vinyl ether:perfluorocyclopr-opene. The copolymer had an inherent viscosity of 0.58 (0.1% solution in benzene at 25 C.).

EXAMPLES 9-22 Other copolymers of perfluorocyclopropene Equimolar quantities of perfluorocyclopropene and polymerizable ethylenically unsaturated monomers (see Table I) were added to a glass tube (18 mm. x 4 mm. ID.) with benzoyl peroxide (5 mg, 2 10 moles). The tube was degassed, sealed and heated at 8085 C. The copolymeric product was charatcerized by its infrared spectrum, by differential thermal analysis, and in some cases by fluorine elemental analysis.

The infrared spectrum of each copolymer was different from that of the corresponding homopolymer of the ethylenically unsaturated monomer. Each copolymer had characteristic absorption at 1730-1700 (strong), 1600 Equimolar quantities of perfluorocyclopropene and tetrafluoroethylene were placed in platinum tubes with catalytic amounts of an initiator, and polymerized at about 3000 atmospheres. Initiators used were azoisobutyronitile, dinitrogen difluoride and perfluoropropionyl perox- 1 e.

Still another sample of the perfluorocyclopropene and tetrafluoroethylene mixture was polymerized by ultraviolet radiation at 2637A. The monomers were mixed under autogenous pressure in acetone.

The infrared spectra of these copolymers differ from that of poly(tetrafluoroethylene). Also, differential thermal analysis revealed that these polymers have glass transition temperatures and melt endotherm curves differing from those of poly(tetrafluoroethylene).

EXAMPLE 24 Perfluorocyclopropene (2.3 mmoles) and vinyl fluoride (4.7 mmoles) were placed in a 7" X platinum tube containing 0.05 mmole of azoisobutyronitrile and heated 8 hours at 75 C. under 3000 atmospheres pressure. An elastomeric copolymer was obtained in 50% yield. The infrared spectrum showed absorption bands at 2980, 1490, 1220, 1180, 1080, 920, and 800 cm.- and differential thermal analysis gave a glass transition temperature of 44 C. These values compare with the following data for vinyl fluoride homopolymer (non-elastomeric) prepared as a control: infrared bands at 2950, 1630, 1450, 1430, 1410, 1360, 1250, 1230, 1140, 1045, 1030, 890, 830, 760, and 720 cm.- glass transition temperature, 33 C.

EXAMPLE 25 Perfluorocyclopropene (2.3 mmoles) and vinylidene fluoride (4.7 mmoles) were copolymerized with 0.05 mmole of azoisobutyronitrile as initiator by the procedure of Example 24. The copolymer, obtained in 62% yield, showed a glass transition temperature of 30 C. A control sample of vinylidene fluoride homopolymer showed no glass transition temperature.

In addition the monomers listed in Table II below, can be employed in the aforedescribed polymerization process to produce copolymers of the two monomers.

TABLE II Comouomers crrg=onooimJ Cyclopropeue Same as abvc..... CIFCCF2 1() D0 CFQ=CFOCH3 F Cl OF2=CFOOF FAF Same as above.

D0 CH CHCflIIn F Br FHC=CHOCH Same as above C1HC=CFC1 o CF2=CFCF3 The monomers of this invention were identified by ordinary analytical techniques. For example, in addition to the data given in the examples, samples of perfluorocyclopropene gave the following spectral data:

F n.m.r.: A triplet (J=43.5 c.p.s.) at 5456 c.p.s. (external Cl CF reference) and a triplet (J=43.5 c.p.s.) at 8184 c.p.s.

Infrared: 1945 (C=C stretch of a strained ring), 1380, 1340, 1200, (CF), 930, 890, and 775 crnr' Mass spectrum: Formula C F (molecular weight 112) and required fragments. Considerable C F CF and C F fragments.

A sample of 3-chlorotrifluorocyclopropene gave the following time-of-flight mass spectrum: Cl /Cl isomer ratio of Cl containing ions verified the presence of one 8 chlorine atom. The parent ions of molecular weight 228 (C1 and 230 (C1 were observed, as Well as a base peak C F requiring a 3-substituted chlorine.

The starting cyclopropanes employed in the methods for preparing the monomers of this invention can be prepared by conventional literature procedures. For example, the 1,2-dihalo-1,2,3-trifluorocyclopropanes and the 1,2,3- trihalo-1,2,3-trifiuorocyclopropanes can be prepared as described by Birchall et al., Proc. Chem. Soc. 1960, 81, and by Mitsch, J. Am. Chem. Soc. 87, 758 (1965).

The monomers of this invention are useful as insecticides, e.g., tetrafluorocyclopropene Was toxic to drosophila at concentrations of 1 part in 300. At this concentration the compound was not explosive; the lower explosive limit being about 1.7 parts in 98.3 parts of air.

The copolymers of this invention form clear self-supporting films and find utility in the usual applications for clear films. For example, a copolymer of tetrafluorocyclopropene and methyl vinyl ether was cast from benzene solution.

The foregoing detailed description has been given for clearness of understanding only and no unnecessary limitations are to be understood therefrom. The invention is not limited to the exact details shown and described, for obvious modifications Will occur to those skilled in the art.

The embodiments of the invention in which an exclusive property of privilege is claimed are defined as follows:

1. 3-halotrifiuorocyclopropenes of the formula wherein X is fluorine, chlorine or bromine.

2. The compound of claim 1 wherein X is fluorine. 3. The compound of claim 1 wherein X is chlorine.

References Cited UNITED STATES PATENTS 3,335,194 8/1967 West, Jr., et a1.

DANIEL D. HORWITZ, Primary Examiner US. Cl. X.R.

Adequately cross-referenced in parent case. 

